Current studies are directed toward a definition of the total nerve supply to the teeth and to gain information on the possible role of the nerves in teeth to dentinogenesis. The initial objective is being carried out by the study of the trigeminal, otic, pterygopalatine, submandibular, cervical sympathetic ganglia and the mesencephalic nucleus of the trigeminal nerve in the pons after injection of H3-HRP (horseradish peroxidase) in tooth pulps. The mesencephalic nucleus is also being studied using quantitative autoradiography and anterograde transport of H3-leucine, by testing for the presence and distribution of the radiolabeled amino acid in the tooth pulp. Studies are also in progress in which the sensory component of the mandibular nerve is sectioned unilateraly. Tooth pulps are then stimulated bilateraly (by cavity preparation) and changes in the proliferation of the cellular components (pulpal fibroblasts and odontoblasts), using H3-thymidine, are determined relative to the repair of the wound (cavity prep).